nosology \nō-ˈsä-lə-jē, -ˈzä-\ noun, probably from New Latin nosologia, from Greek nosos disease + New Latin -logia -logy. circa 1721
1 : a classification or list of diseases
2 : a branch of medical science that deals with classification of diseases
In any discussion, particularly in science, the defining of terms is vital to progress. If you think a term means one thing, and someone else thinks it means something else, then unless you address this difference, you are not going to come to any meaningful agreement.
This problem is particularly apparent in the phenomenon of “Morgellons“. There are two particular terms that cause problems. The first is, obviously, “Morgellons” itself, and the second is “Delusional Parasitosis” (DP). The confusion between these terms has led to the doubly misunderstood (and hence incorrect) statement that “Morgellons is DP”. Morgellons is not DP.
For a doctor, “Morgellons” is a list of symptoms. Itching, lesions, finding fibers, fatigue, confusion and a few others. It’s a rather broad list, and various people define it slightly differently, and the extent to which you have to have all the symptoms varies. Stricker and Savely say you can have Morgellons without finding fibers. Most doctors don’t think that this list of symptoms really defines a new disease, and the conditions of people who self-diagnose with Morgellons is rather better explained by existing diseases.
For the patient however, “Morgellons” is “the disease that is causing my problems”. So if they hear someone say “Morgellons is not real”, it’s like someone said “your problems are not real”. The patient will quite understandably get very angry when someone tells them that their problems are not real, because their problems ARE real.
This is compounded when people talk about DP. The definition of DP will vary based on who you ask. Some people say that if there is a physical condition underlying your false belief in parasites, then that’s NOT DP. DP, they will say, is present when:
The patients have no obvious cognitive impairment, and abnormal organic factors are absent. True infestations and primary systemic diseases that cause pruritus are not involved. Primary skin lesions are not present.
In other words, if the patient has something wrong with them, such as diabetes, or if their formication is caused by a physical condition such as menopause, then they can’t have DP. If they have obvious cognitive impairment, then they can’t have DP either. If they have a skin condition like eczema, or folliculitis, then they can’t have DP.
This restrictive definition of DP allows proponents of Morgellons to say not only that “Morgellons is not DP”, but “people with Morgellons cannot have DP”, since DP is a purely psychiatric condition with one mental symptom, and Morgellons includes both additional physical symptoms (fatigue, tooth loss, etc) , and additional mental symptoms (brain fog, confusion, etc.)
The problem here is not with the Morgellons community, they are actually using definitions of DP to come up with a logically consistent conclusion. The problem here is with the dermatology community for both their broad statements like: “Morgellons is DP” and their simultaneously conflicting statements like: “DP is a single symptom mental illness”. Neither of these statement is correct.
The reality is that Morgellons is a list of symptoms of unknown statistical significance, and DP is the unshakable false belief that one is infested by parasites, and comes in primary, secondary functional, and secondary organic forms.
Dermatologists, of course, appreciate the complexity of the situation, but they do not seem to be communicating it very well. They would make their jobs a lot easier if they made a little effort to communicate these distinctions, both to their patients, and to the media.